| dc.description.abstract | The sorghum shootfly, Atherigona soccata Rondani
is one of the most important pests of sorghum. Since
control measures like the use of insecticides are not
very effective or economical breeding for resistance
could be the answer to the problem in the future.
In this study, the possible mechanisms of
resistance in 5 selected sorghum lines to the sorghum
shootfly, were investigated under greenhouse and field
conditions. These lines: IS-1054, IS-1082, IS-2195,
IS-2312 and IS-3962 were selected for their promising
performance in earlier screening tests.CSH-l, a hybrid
variety from India and susceptible to shoot fly attack
was included as control.
Oviposition preference was studied in a single
choice o~iposition test involving the control (CSH-l)
and each one of the 5 test lines. For antibiosis
studies, the following parameters were considered:
growth and mortality of larvae raised on the test lines
and control, the extent of damage to the shoot, fecundity,
longevity, preoviposition period in the adult flies
and hatching of the resulting eggs.
A randomised complete block design consisting
of 4 blocks was employed in the field experiment in
which the test lines and control were subjected to a
natural insect pest infestation. Observations on
germination, oviposition, dead-heart formation both
in the main plants and in tillers, tillering ability, •
flowering and damage by pests other than the shoot fly
were recorded.
Results of this investigation show that IS-3962
was strongly non-prefe-rred for oviposition by the shootfly
followed by IS-2312. Oviposition non-preference
was present at a higher level in IS-I082 and at low
level in IS-2195 whil~it was lacking altogether in
IS-I054. IS-2312 was very strong in ahtibiosis
followed by IS-3962. IS-2195 had ~ low level of
antibiosis, IS-I054 had the lowest level while it was
lacking in IS-I082. IS-2195 also showed sane tolerance characteristic
In conclusion the best material in terms of
shoot fly resistance is IS-3962 and IS-2312 followed by
IS-2195. IS-I082 has a moderate resistance rating
while IS-I054 has the lowest rating.
The next step in this field of research is
to learn more about the factors responsible for
various mechanisms of resistance identified in
these lines and incorporate them into high yielding
agronomically recommended sorghum varieties.
Further investigation on sources of multiple resistance ,
for shootfly, stemborers and midge would be of great
importance in the breeding of these resistant sorghum
varieties. | en |
